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Complexity of deciding conjugacy of rational relations

The conjugacy problem for rational relations can be stated as follows: ∗∗Input:∗∗**Input:** A rational relation defined by a letter-to-letter finite state transducer T\mathcal{T}, that is, a finite state automaton whose transitions are labeled by pairs of letters (a,b)(a,b) (rather than by single letters). ∗∗Question:∗∗**Question:** Is it true that for every accepting run of T\mathcal{T}, the concatenation a1a2⋯ana_1a_2\cdots a_n of the first components of the labels is a cyclic shift\textit{cyclic shift} of the concatenation b1b2⋯bnb_1b_2\cdots b_n of the second components? That is, does there exist 1≤j≤n1 \leq j \leq n such that: 1) ai=bi+ja_i = b_{i+j} for all 1≤i≤n−j1 \leq i \leq n-j, and 2) ai=bi+j−na_i = b_{i+j-n} for all n−j<i≤nn-j < i \leq n. This problem is known to be decidable (see ‘‘Deciding conjugacy of a rational relation"``\textit{Deciding conjugacy of a rational relation}" by C. Aiswarya, Amaldev Manuel, and Saina Sunny). However, the known decision procedure relies on describing the rational relation using a form of regular expressions. Is there a more efficient algorithm that works directly\textit{directly} on the finite state transducer, without converting it into a regular expression?

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